Density and biomass responses of ephemeral plants to experimental exclusions of small mammals and their vertebrate predators in the Chilean semiarid zone

Density and biomass responses of ephemeral plants to experimental exclusions of the principal small mammal herbivore, Octodon degus (degu), and their vertebrate predators in a semiarid Mediterranean site in north-central Chile were assessed in 1996. Two and four out of 39 plant species showed significant responses to degu removal and predator exclusion, respectively. Total biomass of ephemeral plants was higher in predator-access and degu-access plots. The weak response of ephemeral plants to experimental exclusions in 1996 may have been the result of low numbers of small mammals and vertebrate predators after four years of drought following the 1991–1992 El Nino Southern Oscillation event.